"The waves of fashion that have swept through postwar music, at times with terrorizing impact, have never aroused any interest in me: I believe they confuse technique with content and message" - thus the Swedish composer Allan Pettersson in an interview shortly before his death this summer. He could have easily have been speaking of his fellow Scandinavian, the Finnish composer Aulis Sallinen.

It is well to remember that in Scandinavia the symphony is an unbroken tradition with a relevance, vitality and force scarcely to be imagined by contemporary British composers, and a form to which a composer like Sallinen would automatically turn to express an important idea. It has ceased advancing, and under revitalizing influences like progressive tonality, thematic transformation and metamorphosis is almost as far removed from Brahms as Brahms is from C.P.E. Bach. Sallinen himself describes his own belief that for him symphonic structure and texture should be based on the organic expansion of motifs - melodic, harmonic and rhythmic - and their mutual connection. This process can clearly be seen developing from his first symphony, written ten years ago when he was 35, to the fourth, receiving its first British performances by the Halle Orchestra.

Only the Third (1975) did he move away from the one movement form. This was undoubtedly a result of working on his first opera, The Horseman, which had the effect of loosening up his whole approach to compostion, particularly the Symphony.

His most recent Symphony, the Fourth, is structurally the most expansive and relaxed so far. It was written quickly and occupied him for a period of about two months during the winter of 1978/9 to a commission from the City of Turku. Like the Third, it is cast in three movements: the first is dramatic in character, the second elegiac laeding directly into the finale, andante/allegro. In very general terms the moods are aggression, supplication and reconciliation. Although the language is extremely direct, even traditional, the form is individual and personal.

The opening, marked Andante poco giocoso immediately states two diametrically opposed 'germ cells', one belligerently militaristic and rhythmic, on wind and timps, the other a slow succession of string chords. Both are extremely brief, but practically everything heard in the next 22 or so minutes stems directly from one or other of them. They are promptly developed and combined in various ways. What might be called a principal subject grows out of each: the first short but rich in melodic potential, the other, even more striking, grows from a vigorous development of the second cell into a surging swaggering theme in ¾ time. The movements proceeds rapidly through a number of sections as all the elements are continually reorganized, consolidated, and developed, superimposed in various combinations with sub-themes introduced and developed in bewildering profusion, culminating in a powerful restatement of the second principal subject to the accompaniment of all the other elements.

Nothing more contrasted can be imagined than the simple lines of the second movement, which exactly balances the vehement assertiveness of the first. Headed by the words "Dona Nobis Pacem" it is a simple arch built up from three ideas. A song-like theme - a transformation of elements of both subjects of the first movement - has a poignancy which is reinforced rather than dispelled by a sombre, insistent figure on tenor drum, which interrupts it. An eloquent if restrained climax is built up by an ascending phrase on strings, celeste and tuned percussion before the movement closes with a return to the mood of the opening.

The third and longest movement follows without a break and changes the mood instantly. A dense chord, mezzo forte on brass and strings introduces a restless ostinato passage which recurs several times in various guises. Like the first, the third movement is very tautly constructed but based this time on three main ideas derived from material heard at the opening of the symphony. The process is very typical of Sallinen's approach to thematic construction, with the lines emerging from small intervals, in this case provided by the opening chord. The first theme (very akin to the opening subject of the First Symphony) gives way to a strongly syncopated figure, which in turn leads to a playful, Prokofiev-like scherzo based on the second part of the opening string motif. The composer builds up all three elements into a culmination of masterly simultaneous statement, with accompanying textures developed to a dominating thematic position. In complete contrast to the anguished despair of the finale to the Third Symphony, the fourth ends peacefully with echoes of the very first germ cell, now pianissimo on strings, to reconcile the disparate combative forces that have been at war throughout. Although full of violence and colour, the 4th Symphony is a triumph of organized thematic growth and unified overall structure.